1. Field of Invention
This invention relates to autonomously operating solar powered swimming pool skimmers, specifically to those with mechanisms diverting them from collisions with swimming pool walls.
2. Background of the Invention
Most dirt entering a swimming pool first rests on the water surface as floating debris for a period of hours before sinking. Hand held skimmer nets are labor intensive, and debris typically sinks before a skimming opportunity arises. In the process of using hand held skimmer nets, debris is inadvertently caused to sink to the bottom. Skimmers associated with the main pool filtration system typically operate on timers that also typically miss skimming opportunities. They additionally require immense amounts of electricity relative to the skimming effort being performed, and are frequently precluded from being used by automatic bottom scrubbing devices that are powered by the same main pool filtration system.
Bow mounted paddle wheel style impellers have long been recognized as the most energy efficient dirt, debris, and oil skimming device in harbor skimmers, and have more recently been proposed for use on autonomous self propelled swimming pool skimmers powered by solar cell arrays. This style impeller does not require high skimmer velocity, which is difficult to obtain under limited solar power.
Such solar pool skimmers have the advantages of low power usage, availability when most needed, no cords or hoses, and the ability to propel themselves about the pool. Several such devices have been proposed. Their design is constrained by extremely low energy levels available, the need to prevent backwash of debris back into the pool when turned off, dealing with debris clogged impellers or water entrances, and the difficulty of navigating out of tight corners and away from obstructions, such as ladders and pool toys. Several notable solar skimming devices have been proposed:
U.S. Pat. No. 5,106,492 to Distinti et al. uses a bow paddle wheel effectively for propulsion and skimming, and one embodiment uses a floating weir to limit debris backwash when the unit is off. Such floating weirs function well on high power harbor skimmers, but presents considerable resistance to flow in low power solar skimmers. It has a single un-powered bow deflector wheel on a flexible boom. This deflects the skimmer away from certain wall collisions, but allows it to become stuck in sharp corners, from which there are no means to escape. It includes an interesting warning alarm for a full filter, but that alarm relies on measuring the weight of essentially weightless floating debris.
U.S. Pat. No. 4,900,432 to Arnold et al. uses bow a paddlewheel to throw debris over a barrier to prevent backflow, and uses a secondary sideways thrusting impeller to steer away from a wall. The fixed barrier above water level works well for large harbor skimmers, but creates too great of a workload for a small solar device and severely inhibits propulsion. It also suffers from large debris becoming stranded on top the fixed barrier in normal operations, with no means available for its automatic removal. The side thruster steer away from many stuck positions, but doesn't extract the skimmer from acutely angled corners.
U.S. Pat. No. 5,128,031 to Midkiff uses a pump downstream of a filter rather than the conventional bow paddle wheel, diverting the thrust of the outlet of the pump in a random fashion. Then he employs a solenoid valve to divert the thrust through backwards nozzles in response to bow impacts. This involves forward ram style of debris collection requiring a speed that is beyond the power capacity of reasonable size solar cell arrays. Ram style of filtration requires quite high forwards velocity, difficult to achieve in a solar powered device, and a positive mechanism to inhibit backwash of debris when turned off. Midkiff did not propose any sort of backwash preventing means on the rather wide mouthed water entrance of his invention.
U.S. Pat. No. 6,074,553 to Haski similarly employs a ram filter, and an underwater impeller, utilizing forward protruding rods to act on rear rudders or thrust nozzles, thereby causing collisions to divert the thrust to one side or the other. His device lacks any backwash prevention or mechanism to allow his skimmer to extract itself from acute angled corners. Like other similar devices, it will work well for a time, but requires human intervention frequently when it finally becomes stuck.
Therefore swimming pool skimming devices heretofore known suffer from a number of disadvantages:
a) Manual skimmer nets, while cheap and effective, are labor intensive and typically miss catching debris before it sinks.
b) Many skimmers commonly in use rely on the main swimming pool filters, typically requiring hundreds or thousands of times as much electric power as do autonomous solar powered skimmers. As a result, they are typically not run frequently enough to catch debris before it sinks.c) Other skimmers require cords and hoses stretched across the pool, creating a hazard for swimmers.d) Proposed solar skimmers lack autonomous ability to extract themselves from the worst stuck positions.e) Proposed solar skimmers lack effective and foolproof means of preventing backwashing of debris out of the filter when stopped.f) Most proposed solar skimmers require more power for skimming and propulsion than is available from reasonable size solar cell arrays.g) Proposed solar skimmers loose essentially all propulsive effect when used with filters fine enough to filter the finest of dust floating on a pool surface. This fine dust represents a sizeable fraction of the total filtration load.h) All other skimmers lack provisions for dealing with the severe corrosion problems of motors in swimming pool environments.